Aluminum (Al) concentration was assessed in deciduous teeth in relation to sex, year of birth, tooth type, and the presence of caries and roots. Three hundred and twenty-three deciduous teeth from children born during the period 1952 93 in a county in southeast Sweden were sampled, and the Al content determined by graphite furnace atomic absorption spectrophotometry. The arithmetic mean of the Al concentration was 0.58 +/- 0.64 ppm dry weight (mean +/- standard deviation) and differed significantly between incisors (1.05 +/- 1.04 ppm) and canines (0.48 +/- 0.50 ppm) and between incisors and molars (0.53 +/- 0.55 ppm). A significant difference was found between teeth with and without caries. No significant differences were found between sexes. The Al concentration correlated significantly with tooth weight for incisors (r = -0.47) and canines (r = -0.45) but not for molars (r = 0.03). No significant change in Al concentration was found over time. Caries-free deciduous molars are suggested as the most useful teeth for biological monitoring of aluminum.